When friends at university talked about the Higher School Certificate or their Australian Tertiary Admission Rank (ATAR), Ms Clemmett, 38, would avoid the subject or grab a coffee.

When she got into law, after many years of full-time work - often in menial jobs - she felt like she "was a bit of a fraud".

Later, working as a paralegal during university, Ms Clemmett recalled wondering what "would happen if all those barristers, and Commissioner Cole, knew what a fraud I was - that I was a high school dropout, from Lismore, sitting in the middle of their royal commission".

Now proud of her achievements, she has decided to go public to send the message to the 78,000 NSW high school students about to sit the HSC next week that it is not the be all and end all.

"It is important that kids get the message that the HSC is just a period in their lives, and there is a whole world after it," she said.

At an assembly at her old school, Kadina High in Lismore last month, she came clean with the secret she has carried since she was a 17-year-old in 1996.

"It is ... 21 years since I dropped my bundle, dropped out of school, and spent about a year on Centrelink benefits, wondering what life was all about, what to do with it, and why.

"There you have it: the thing that for years I felt was something of which to be ashamed. I never obtained a Higher School Certificate. I am a high school dropout."

Her "failure" made her depressed and she had contemplated suicide, she said.

Lane Cove clinical psychologist Elise Lowick told Fairfax Media she was fully booked with students suffering "incredible stress" - either those now starting the HSC year or others about to sit exams.

Dr Lowick, who has been counselling young adults and adolescents for 25 years, said students were told to do their best. But often family and the school believed "nothing BUT the best is acceptable" with a poor score seen as reflecting equally on family and school.

"In the end, the HSC is just a brief period in one's life. However, for many, it defines their life. They will hide their marks from peers, they will hide themselves from peers, and hide and pull away from parents.

"It is not worth losing a child's life over a low mark. Water and feed them, do not put extra pressure on them. Yes,they are on social media. Yes, they may be looking at YouTube and Facebook. But in fact, they may also be studying. It is just a mark, not a definition of who they are."

Professor of educational psychology at the University of NSW Andrew Martin said the "blowtorch of competition, competitive pressure, has steadily turned up over the years, and I think that is that happening at a younger age".

"Society still maintains this narrow lens [success is a high ATAR and going to university] of what we define as a success," he said.

"I would love a greater narrative about success stories that happen through non traditional and vocational pathways. They are there in abundance in many TAFE and VET pathways."

While a high ATAR influenced what course a student could do at university and their first-year results, research had shown by the second year it had no influence, Professor Martin said.

"It is not long before it becomes part of your history, but your effort, your application, your persistence, your temperament, all these factors shape the life you live," he said.

A perception of inadequate competence can make them more likely than boys to dwell on their shortcomings, and less likely to take credit for success, he says.

"Taken far enough, this can lead to what is known as the "imposter syndrome", a feeling of being secretly inadequate to one's role, and at constant fear of being found out as mediocre and not up to the high demands of the job. This can follow girls into their adult and professional life."

Ms Clemmett's path to the law was circuitous and hard. After a dismal year on the dole, she started a government-funded training program at St Vincent's Hospital in Lismore where she estimated her real wage was $3.20.

She'd often work late, start early, impressing others with her intelligence and work ethic. By 20, she was working in Sydney, managing the diaries of 42 anaesthetists.

"If I didn't do my job, there would be a surgeon standing around at hospital waiting to start the operation with no anaesthetist. Some of them thought I was too young ... Damn I worked hard to prove them wrong," she told the students.

When she got into university as a mature-age student, the group asked how much she needed to earn to support herself while studying.

"If you drop your bundle, just pick up the pieces you can carry and work with them. Do something, and do it to the best of your ability. Make meaningful connections and use them. People will respect you if they see you work hard."

"I have been told that my life has been like a series of lily pads, in which I just jump from one to the next. But I made those lily pads, dammit. And you can make yours," she told her old school.

Ms Clemmett believes that, had she stayed at school to sit the HSC after she dropped her bundle in 1996, she wouldn't have become a barrister.

"There is no prospect I would be where I am today. I wouldn't have thought to study law. I just worked with what I felt I could at the time. And I worked my arse off, consistently. I worked my way through from shit kicker jobs, to well paying jobs, to excelling at university. I found a career I love."

When she donned her barrister's wig and gown, the applause at the school was thunderous.